This invention relates to reciprocating slat conveyors. More particularly, it relates to a method and apparatus for connecting conveyor slats to transverse drive beams by clamping onto bottom flange portions of the conveyor slats.
A reciprocating slat conveyor comprises a plurality of conveyor slats that are mounted adjacent each other for longitudinal reciprocation. A typical reciprocating slat conveyor system is disclosed by U.S. Pat. No. 4,793,469, granted Dec. 27, 1988, and entitled Reduced Size Drive/Frame Assembly For A Reciprocating Floor Conveyor. The conveyor slats are divided into three sets, identified by the numerals xe2x80x9c1xe2x80x9d, xe2x80x9c2xe2x80x9d, and xe2x80x9c3xe2x80x9d, respectively. The slats are arranged in a plurality of groups, with each group including adjacent slats, one from each set. Referring to FIGS. 2-6 of U.S. Pat. No. 4,793,469, advancement of a load xe2x80x9cLxe2x80x9d is accomplished by the simultaneous movement of all three sets of slats. The slats are then retracted, one set at a time. The conveyor includes three transverse drive beams, one for each set of slats. The slats of each set are connected to the corresponding drive beam by a plurality of connectors that are attached to the drive beam. Each drive beam is connected to a drive motor that is operated for selectively reciprocating the drive beam and the slats that are connected to it. The slats are also supported by bearings positioned over longitudinal guide beams.
FIG. 1 herein is like FIG. 11 in U.S. Pat. No. 4,793,469. It shows a drive assembly comprising a frame 10, three drive units 12, three transverse drive beams 14 and slat connectors 16 for twenty four slats 18 (FIG. 2 herein). In the conventional procedure for installing a reciprocating slat conveyor, the drive assembly is first installed. Then, the conveyor slats 18 are positioned above the drive assembly. A worker goes below the drive assembly and drills upwardly through openings in the connectors 16 to form corresponding openings in each slat 18. Then, a nut is held in place below the connector 16 while a bolt is inserted through the drilled hole in the slat from above the slat and is threaded into the nut. This conventional procedure is cumbersome due to the need to drill metal parts at a location in the field, removed from the fabrication facility, and the necessity for a worker to access the area below the drive assembly.
U.S. Pat. No. 6,000,530, granted Dec. 14, 1999, and entitled Drive Beam Connector And Connection Method provides a specific connector for securing the conveyor slats to the transverse drive beams without requiring access to the area below the drive beams. It also provides for the use of conveyor slats that are predrilled in the fabrication facility, making it unnecessary to drill the conveyor slats in the field. FIG. 2 herein shows a conveyor slat 18 connected to a connector 16 that includes the floating nut bar 20 that is inside the connector 16. The connector 16 is connected to a transverse drive beam 14 by a series of bolts 22. The nut bar 20 is in a space 24 inside the connector 16. The top 26 of the conveyor slat 18 is provided with predrilled openings 28 that are sized and shaped to receive the heads 30 of screw fasteners 32. Openings 28 are countersunk openings and the fastener heads 30 are shaped to fit down into the countersinks. Threaded shank portions 36 of the screw fasteners 32 thread into a threaded opening 38 in the nut bar 20. The nut bar 20 floats sideways and allows the threaded shanks 36 of the screw fasteners to mate with the threaded opening 38. Bolts 22 hold the connector base 40 tight against the drive beam 14. Screw fasteners 32 hold the slat top 26 tight against the connector top 42.
While developing the invention that is disclosed and claimed in U.S. Pat. No. 6,000,530, it became apparent that there was a need for a way of securing conveyor slats to the drive beams without the use of screw fastener holes in the conveyor slats. The primary object of the present invention is to provide such a system.
The present invention is directed to an apparatus and method for connecting a reciprocating conveyor slat having an inner space and laterally spaced apart bottom flanges to a drive beam that is situated below the bottom flanges. The apparatus is basically characterized by an upper clamp member that is fittable into the inner space of the conveyor slat and which has side portions positionable above the bottom flanges. A lower clamp member is connected to the drive beam. It has side portions that are below the bottom flanges of the conveyor slat. The conveyor slat is positioned to place its bottom flanges vertically between the side portions of the upper and lower clamp members. Then a bolt or bolts are tightened to pull the upper clamp member downwardly so as to firmly clamp the bottom flanges of the conveyor slat between the side portions of the upper and lower clamp members. The clamp members firmly grip onto the bottom flanges of the conveyor slat, firmly connecting the conveyor slat to the drive beam, without the need or use of fasteners that extend through openings in the top of the conveyor slat.
The bolt may have a head and a threaded shank and be insertable upwardly through openings in the drive beam and the lower clamp member and be threadable into a threaded opening in the upper clamp member. Or, the bolt may project downwardly from the upper clamp member, through openings in the lower clamp member and the drive beam, and be connected to a nut that is below the drive beam. In the first embodiment, a wrench is attached to the bolt head and is rotated to move the threaded shank of the bolt into a threaded opening in the upper clamp member. In the second embodiment, the wrench is attached to the nut and is used for threading the nut onto the threaded shank of the bolt. In both embodiments, the movement of the threaded shank of the bolt through the threaded openings in the upper clamp member or the threaded openings in the nut acts to pull the upper clamp member downwardly so as to firmly clamp the bottom flanges of the conveyor slat between the side portions of the upper and lower clamp members.
Preferably, at least one spring is positioned vertically between the upper and lower clamp members. The spring is of a size and strength sufficient to urge the upper clamp member away from the lower clamp member when the bolt is loosened. Initially, the bolt is tightened to such an extent that the upper clamp member is connected to the lower clamp member and the drive beam but the side portions of the upper clamp member are spaced vertically above the side portions of the lower clamp member an amount sufficient to allow movement of the bottom flanges of the conveyor slat into a position vertically between the upper and lower clamp members.
In preferred form, a plurality of bolts are employed. They are spaced apart longitudinally of the conveyor slat and are positioned laterally between the bottom flanges of the conveyor slat. Preferably also, at least two springs are used. The springs are spaced apart longitudinally of the conveyor slat. The upper clamp member may be formed to include a downwardly directed upper socket for each spring, to receive the upper end portion of the spring. The lower clamp member would then be formed to include an upwardly directed lower socket for each spring, for receiving the lower end portion of the spring.
According to an aspect of the invention, the side portions of the upper clamp member have recesses and projections that are directed downwardly towards the side portions of the lower clamp member. The side portions of the lower clamp member have recesses and projections that are directed upwardly towards the side portion of the upper clamp member above it. The projections on each clamp member are in general alignment with the recesses on the other clamp member. As a result, when the bolts are tightened, the projections and recesses are moved together and against the bottom flanges of the conveyor slat. They form wrinkles in the bottom flanges and these wrinkles serve to resist relative longitudinal movement of the conveyor slat relative to the transverse drive beam when a drive force is applied.
In preferred form, each side portion of the upper clamp member has opposite end parts and each side portion of the lower clamp member has complementary end parts. When the bolt(s) are tightened, the upper and lower end parts make clamping contact with upper and lower surfaces of the conveyor slat flanges. The recesses and projection are longitudinally between the opposite end parts of the side portions of the clamp members. The end parts grip the bottom flanges of the conveyor slat without deforming them. The projections and recesses deform the bottom flanges of the conveyor slat in their extent longitudinally between the end parts.
According to a method aspect of the invention, the conveyor slat is positioned so as to position the upper clamp member inside of the conveyor slat, horizontally between the side parts of the conveyor slat and vertically between the top and the bottom flanges of the conveyor slat. The bottom flanges of the conveyor slat are positioned vertically between the clamping surfaces of the side portions of the clamp members. The bolt is tightened so as pull the upper clamp member downwardly and firmly clamp the bottom flanges of the conveyor slat between the side portions of the upper and lower clamp members. One of the clamp members may include stop lugs that are laterally between the bottom flanges of the conveyor slat. These stop lugs make contact with the other clamp member and limit the amount of movement of the clamping surfaces together.
The invention also includes providing the conveyor slats with slide bearings onto which the conveyor slats can be snap fitted. The conveyor slats are positioned over the bearings and over the lower clamp members, with the bolts aligned with bolt receiving openings in the lower clamp member. Then, the conveyor slats are pushed downwardly so as to snap the conveyor slats onto the bearings and move the bolts through the bolt receiving openings in the lower clamp member. Then, from below the drive beam, a nut is attached to each bolt and is tightened so that the upper clamp members will be drawn downwardly into clamping engagement with the conveyor slat bottom flanges.
Other objects, advantages and features of the invention will become apparent from the description of the best mode set forth below, from the drawings, from the claims and from the principles that are embodied in the specific structures that are illustrated and described.